184 ILLINOIS STATE ACADEMY OF SCIENCE 



the stem, leaf 3 had a portion of the stem and also the 

 opposite leaf attached. These leaves were suspended 

 by means of threads from the top of an aquarium. in a 

 saturated atmosphere in such a manner that their tips 

 were submerged in water. 



After 10 days the results obtained with B. calycinum 

 were essentially those obtained by Loeb. After 16 days, 

 however, roots had developed at the base of the petiole in 

 2 of the completely isolated leaves suspended in satu- 

 rated air, and by the end of 5 weeks shoots had appeared 

 also. These results are contrary to those obtained by 

 Loeb who says, "The advantage of this plant for the 

 study of the problem of regeneration lies in the fact that 

 shoots can grow out only from definitely located buds in 

 the stem and in the notches of the leaf." 1 In another 

 place he states, "The stalk of an isolated leaf without 

 any piece of stem is not capable of giving rise to any re- 

 generation. Such a leaf will form adventitious roots and 

 shoots in its notches very rapidly." 



B. crenatum gave several results different from those 

 obtained by Loeb with B. calycinum. After 10 days, 

 growth had occurred in leaf 1 on the aerial as well as on 

 the submersed portion of the leaf, and in mature flower- 

 ing plants the growth from the aerial was more vigorous 

 than that from the submersed portion of the leaf. In 

 leaf 2 from mature plants the bud grew out from the 

 opposite axil as stated by Loeb. In many cases, however, 

 shoots appeared in both axils. In the leaves from very 

 young plants, only the bud from the adjacent axil had 

 developed. With B. calycinum, Loeb reports no develop- 

 ment of the axilliary buds in leaf 3. In B. crenatum 

 shoots appeared from both axils in all the specimens. 

 There was also some notch growth on most of the leaves. 



Plate I shows these leaves at the end of 5 weeks. Leaf 

 1 with the best notch growth had developed a large shoot 

 at the end of the petiole. The shoots and roots in both 

 axils of leaf 3 were as large as those in leaf 2 and the 

 growth from many notches was nearly as vigorous as 

 that in leaf 1. Leaf 2 showed considerable notch growth. 

 All the drawings given in this article were made from 

 photographs of the specimens. 



